BATOCRINIDZ. 463 
Dorycrinus missouriensis (SHuMARD). 
Plate XLIII. Fig. 6, and Plate XLV. Figs. 18a, b, c, and 14. 
1855. Actinocrinus missouriensis —SHUMARD; Geol. Surv. of Missouri by Swallow, Part II., p. 190, Plate 
A, Figs. 4a, 6, ¢c. 
1873. Dorycrinus missouriensis — Munk and Wortuxn; Geol. Rep. Illinois, Vol. V., p. 380. 
1881. Dorycrinus missourtensis —W. and Sp.; Revision Paleocr., Part II., p. 179 (Proceed. Acad. Nat. 
Sci. Phila., p. 353). 
Syn. Actinocrinus desideratus Havi; 1861, Prelim. Descr. of New Paleoz. Foss., p. 2, and Boston 
Journ. of Nat. Hist., p. 353. 
Syn. Dorycrinus desideratus — Murx and WortHEn; Geol. Rep. Illinois, Vol. V., p. 380. 
A variable species, remarkable for the extravagant development of its 
basal plates. Besides it differs from other species of this genus in the com- 
paratively greater height of the dorsal cup, and the abrupt spreading of the 
distichals and palmars, which stand almost at right angles to the radials and 
costals. Calyx a little longer than wide; the ventral disk from one fifth to 
one fourth shorter than the dorsal cup. Plates thick, from almost flat to 
strongly nodose, the nodes upon the radials transverse and most conspicuous. 
Base extremely large and heavy, spreading abruptly outward; its dia- 
meter in extreme cases equaling the width of the dorsal cup at the arm 
regions, and reaching a depth as much as 15mm.; interbasal sutures gener- 
ally grooved and frequently notched. Radials about as long as wide; the 
sides nearly parallel; subquadrangular in outline; the sloping upper faces 
very short; the upper face concave. Costals very small, both together not 
more than half the size of the radials; their surfaces almost flat; the first 
quadrangular, twice as wide as long; the second one no longer but some- 
what wider, and pentangular. The posterior rays have but one distichal, 
which is quite small and axillary, and gives off from each side a single 
palmar. The antero-lateral rays have two distichals, of which the second is 
twice as long as the first; the anterior ray generally has two distichals to 
the left and one to the right, followed by palmars; but this ray also occa- 
sionally has no palmars, and two distichals in both divisions. The arm- 
bearing plates, whether distichals or palmars, are twice as long as the 
preceding plate. The arms normally consist of fifteen pairs, arranged 
in groups of 4, 2, and 38, with wide and deep interspaces between the 
rays; they are short, rather stout for the genus, and bifurcate on a small 
trigonal axillary, which occupies the same facet with the proximal arm 
plates. Arm joints of medium size, and each fourth piece is produced 
